Google bigquery 将列值作为日期部分参数传递

我试图生成一个工作日的字符串数组，并使用它查找一个月内每天出现的次数

我在BigQuery上使用标准sql

我的问题看起来像

with weeks as (select array['SUNDAY','MONDAY','TUESDAY','WEDNESDAY','THURSDAY','FRIDAY','SATURDAY'] as wk)
select DATE_DIFF('2019-01-31','2019-01-01',WEEK(wk)) AS week_weekday_diff 
from weeks, unnest(wk) as wk

---

但是，查询失败，出现错误

，需要一个星期的有效日期部分参数，但找到wk

。wk是一个列值，包含周中的天数，

Week

是一个函数，它需要文本

DAYOFWEEK

。是否有一种方法可以将列值作为参数传递

尝试您的查询时，我注意到返回的错误是：

select DATE_DIFF('2019-01-31','2019-01-01',WEEK('WEDNESDAY')) AS week_weekday_diff; 

由于功能周（）预计会出现以下情况：

select DATE_DIFF('2019-01-31','2019-01-01',WEEK(`WEDNESDAY`)) AS week_weekday_diff; 

或

---

我认为WEEK（）只接受公开格式的WEEKDAY，因此任何字符串都不应有效。

下面是BigQuery标准SQL

错误“需要周的有效日期部分参数，但找到wk”

结果

Row weekday     cnt  
1   SUNDAY      4    
2   MONDAY      4    
3   TUESDAY     5    
4   WEDNESDAY   5    
5   THURSDAY    5    
6   FRIDAY      4    
7   SATURDAY    4    

WEEK(<WEEKDAY>): Valid values for WEEKDAY are literal SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, and SATURDAY.   

#standardSQL
WITH weekdays AS (SELECT ['SUNDAY','MONDAY','TUESDAY','WEDNESDAY','THURSDAY','FRIDAY','SATURDAY'] AS wk)
SELECT wk[ORDINAL(pos)] weekday, COUNT(1) cnt
FROM weekdays, 
  UNNEST(GENERATE_DATE_ARRAY('2019-01-01','2019-01-31')) day, 
  UNNEST([EXTRACT(DAYOFWEEK FROM day)]) pos
GROUP BY pos, weekday
ORDER BY pos

Row weekday     cnt  
1   SUNDAY      4    
2   MONDAY      4    
3   TUESDAY     5    
4   WEDNESDAY   5    
5   THURSDAY    5    
6   FRIDAY      4    
7   SATURDAY    4